In the manufacture of integrated circuit devices, it is desirable to test each device before it is shipped and/or assembled onto a printed circuit board of a large and expensive equipment. Due to production requirements, handling and testing of such integrated devices are carried out in extremely high rates, for instance, in excess of about 5000 devices per hour per machine. When operating at such speeds, testing of the integrity and functionality of each device must be accomplished within a fraction of a second, typically less than 300 milliseconds. In addition, each test should be accurate and reliable. To maintain a predetermined quality assurance, the lower the reliability of a test, the greater is the reject rate; as a result, some devices in working condition may be rejected as defective.
Typically, in a semiconductor test, a pair of bifurcated Kelvin contacts 20 is brought to contact each terminal 12 of the semiconductor device or device under test (DUT). Each pair of bifurcated Kelvin contacts 20 has a contact probe 22 and sense probe 24. Each probe 22,24 is a slender strip of resilient and highly electrical conductive material, and establishes electrical connection between the DUT and a test circuitry or tester 90; the contact probe 22 carries a signal for testing the DUT, whilst the sense probe 24 has high input impedance and is used for sensing a voltage on the same terminal 12 of the DUT. In use, the sense probe 24 is operable to compensate for the contact resistance between the DUT terminal 10 and the contact probe 22. FIG. 1 shows such a prior art semiconductor testing apparatus 10. As shown in FIG. 1, a probe holder 30 separately holds the contact 22 and sense 24 probes together, while a contactor holder 50 holds all the probes 22,24 together.
During semiconductor device testing, the test signals are applied onto the terminal within a short contact time. As a result, steep step-like voltages and currents are supplied through the contact probe 22 of the bifurcated Kelvin contacts 20. Coupled with relatively long electrical paths between the tester 90 and the DUT, the test signals are distorted by parasitic impedance and inductance along the electrical path and parasitic capacitance between adjacent electrical paths. For example, due to steep step-like current surges through the Kelvin contact probe 22, the reference voltage from the tester 90 is distorted and caused so-called ground noise.
U.S. Pat. No. 6,064,218 assigned to PrimeYield Systems, Inc. discusses a test apparatus for testing a peripherally leaded electric package. The test apparatus includes a contactor, an interface board and test electronics. The contactor includes cantilevered spring contacts and an interposer. The interposer includes a plurality of angled conductors, each conductor for connecting a cantilevered spring contact to a corresponding contact pad disposed on the interface board to complete electrical paths to the test electronics.
Despite development in the field of this invention, it can thus be seen that there exists a need for another contactor assembly system for testing semiconductor devices.